1. Field of the Invention
The present invention relates to printing materials utilizing the light sensitivity of silver halide and particularly to positive type printing materials which are presensitized (hereinafter called a presensitized printing plate).
2. Description of the Prior Art
Hitherto, positive type presensitized printing plates using silver halide emulsions have been known, for example, P.M.T. Process (trade name of Eastman Kodak), Mitsubishi Silver Master (trade name of Mitsubishi Paper Mills, Ltd.). However, the plate making process using such is complicated and the resulting printing plates have a low printing durability or a low ink receptivity. Although presensitized printing plates using direct positive type silver halide emulsions also are known as disclosed in U.S. Pat. No. 3,597,201 and Japanese Patent Application (OPI) No. 15502/74, the light sensitivity of these printing plates is low. According to the present invention, these defects have been eliminated.